我国部分地区H9亚型禽流感病毒血凝素基因序列比较与遗传发生关系分析

为从分子水平掌握我国H9亚型AIV的遗传变异情况和流行规律，本研究汇集近年来从我国12个省、市、自治区的发病鸡群中分离到的23株H9亚型禽流感病毒，通过RT-PCR方法和核苷酸序列测定获得了23个毒株的HA基因cDNA核苷酸序列。核苷酸和推导的氨基酸序列同源性比较结果表明，这些毒株HA基因的核苷酸序列同源性为94．1％～100％，氨基酸序列同源性为95．4％～100%；将这23个毒株和来自亚洲及世界其它地区的另外31株的HA基因cDNA序列同源性进行比较发现，分离自香港的HK170499株与日本的2个毒株关系较近；氨基酸序列分析发现，CKGS199、CKTJ196、CKTJ296、CKSH300和CKBJ197五个毒株各发生了一个潜在的糖基化位点的丢失。54株H9亚型AIVHA基因55bp～1152bp的氨基酸序列分析发现，裂解位点尽管有10种基序，但本研究中的23株和近年来从我国大陆和香港地区的分离的毒株则均为RSSR↓GLF；构成受体结合位点的191位氨基酸有一个规律，即所有中国大陆毒株与部分香港毒株都为N，其它毒株均为H，141aa～143aa处的糖基化位点有与191aa类似的规律，即：凡是191aa为N的毒株，该处均为NVS（CKBJ194除外），凡是191aa为H的毒株，则该处均为NVT；遗传发生关系分析，中国大陆毒株处于欧亚谱系的第一支。本研究结果表明近年来我国鸡群中H9N2亚型禽流感病毒的感染流行可能有一个共同的来源，这为制定防治该亚型禽流感流行的有效对策提供了重要的科学依据。

Comparison of Sequences of the Hemagglutinin Gene and Phylogenetical Analysis of H9 Subtype Avian Influenza Viruses Isolated From Some Regions in China

In order to explore the genetic mutaions of the hemagglutinin(HA) gene and the law of molecular epidemiology of H9 subtype avian influenza viruses in China, 23 H9 subtype avian influenza viruses(AIVs) were isolated from l2 provinces of China in recent years. Their nucleotide sequences of cDNA of HA gene were determined by RT-PCR and sequencing. Their nucleotide and putaive amino acid sequences homology was compared. The results showed that their nucleotide sequence homology was from 94.l % to l00 % and that amino acid sequence homology was 95.4 % to l00 %. The sequences of the HA gene of these isolates were analyzed and compared with that of another 8 isolates from reference. The similedty indicated that HKl70499 isolated from Hong Kong was close to the 2 isolates of Japan. And of the 3l isolates with complete HA gene sequences there were 5 isolates, HA gene of which were loss of one potelltial glycosylation site, which were CKGSl99, CKTJl96, CKT296, CKSH300 and CKBJl97. Then l098 nucleotide regions (bases 55 to 1 152) of HA gene of 23 isolates in this study were analyzed phylogenetically and compared with sequences from 31 H9 subtype viruses available in the GenBank database. Although considerable variation at the cleavage sites of the different viruses was observed, giving l0 different amino acid motits, none had multiple basic amino acids that correlate with highly pathogenic avian influenza(HPAI) isolates. Examination of amino acid sequences involved in repeptor binding site(RBS) revealed that the amino acid residue at position 191 characteristically distributed in the 54 isolates, that is, this amino acid residue of the isolates of mainland China and several Hong Kong strains was Asn(N) and that of the others was His(H). And the l4l ~ l43 amino acid residues, involved in forming the potential glycosylation sites, had the similary characteristic distribution with the 191aa position. The isolates with Asn-191. excluding CKBJ197, had NVS in the position l4laa~l43aa, meanwhile those with His-191 had NVT.Twenty-six mainland China isolates was genetically in Eurasian lineage but did not show distinctly geographical and temporal relationship. It is concluded that in recent years H9N2 subtype AIV, circulating in chicken flocks of mainland China, may have a common origini. These findings provides importan basis for establishment of scientifically preventive measurements to control H9 subtype avian influenza.